Load lifting jacks

ABSTRACT

A load lifting jack comprising a pair of guide rails connected in parallel relation with each other by a pin and a connecting member at their both ends so that a rectangular frame is provided, a lifting arm carrying at its one end a load engaging head, a screw shaft rotatably supported within the frame, the screw shaft carrying thereon an internally threaded nut to which the lifting arm is pivoted at its one end, link members pivoted at their one ends with respect to the lifting arm at an intermediate position thereof, a base on which the pair of guide rails is pivotally mounted by the said pin, the base having one or more pairs of aligned notches on its flanged portions with which said one ends of the link members are selectively engageable, and a linking or supporting member which rotatably supports the screw shaft at its one end and inside of the frame but bears the thrust of the screw shaft.

United States Patent [191 Yamazaki July 17, 1973 LOAD LIFTING JACKS [73]Assignee: Aisin Selki Kabushllti Kalsha, Kariya City, Aichi-Pref, Japan[22] Filed: June 23, 1971 [2]] Appl. No; 155,736

[52] US. Cl. 254/126 [51] Int. Cl. B661 3/08, B66f 3/36 [58] Field ofSearch 254/126, 124, 8 R

[56] References Cited UNITED STATES PATENTS 2,469,048 5/1949 Manke254/126 2,587,067 2/1952 Sachtleber 254/126 2,613,914 10/1952 Wallace254/126 X FOREIGN PATENTS OR APPLICATIONS 1,082,067 9/1967 Great Britain254/126 Primary Examiner-Othell M. Simpson Attorney-James E. Mrose etal.

[57] ABSTRACT A load lifting jack comprising a pair of guide railsconnected in parallel relation with each other by a pin and a connectingmember at their both ends so that a rectangular frame is provided, alifting arm carrying at its one end a load engaging head, a screw shaftrotatably supported within the frame, the screw shaft carrying thereonan internally threaded nut to which the lifting arm is pivoted at itsone end, link members pivoted at their one ends with respect to thelifting arm at an intermediate position thereof, a base on which thepair of guide rails is pivotally mounted by the said pin, the basehaving one or more pairs of aligned notches on its flanged portions withwhich said one ends of the link members are selectively engageable, anda linking or supporting member which rotatably supports the screw shaftat its one end and inside of the frame but bears the thrust of the screwshaft.

7 Claims, 5 Drawing Figures PATENTEU 7375 3. 745. 307

' sum 1 or 4 Y INVENTOR. SHINICHIRO YAMAZAKI. BY

ATTORNEY m nnow 1 sum 3 or 4 INVENTOR. -HINICHlRO YAMAZAKI ATTORNEY jPAIENTED JUL 7 sumu nr 4 INVENTOR. S HIN l CHIRO YAMAZAKI QM 672px,ATTORNEY.

LOAD LIFTING JACKS BACKGROUND OF THE INVENTION This invention relates toa jack comprising a four sided linkage adaptable to be used for liftingthe body of an automotive vehicle.

Multiple-lever mechanisms have been adapted to uses in jacks for liftingthe body of an automotive vehicle. These mechanisms have been usedextensively, but they involve some risk that, when used, displacement ofthe load during operation will cause the jack to incline or fall. Whensuch a jack is operated against a load, a body portion with which theload engaging head of the jack engages usually travels in an arcuatepath in an imaginary plane perpendicular to the horizontal. This arcuatemovement of the body portion will in turn cause the load engaging headto displace horizontally. Due to the displacement of the load engaginghead, the jack tends to incline relative to the ground or to fall down.This deficiency is considered a great disadvantage and short-coming inpractice, in that it is often necessary for most applications to set thebase of the jack at an eccentric position on the ground in anticipationof such displacement so that the possible inclination of the jack may beoffset as the jack operates. It requires considerable skill to find aposition on the ground of proper eccentricity at which to set the jackbase.

It is a principal object of the present invention to provide a loadlifting jack, the load engaging head of which may be shifted as the loadshifts while the base remains stationary on the ground.

It is another object of the present invention to provide a load liftingjack in which the load engaging head may be moved upward or downward toengage the head with a body different heights rapidly when no load beingapplied to the jack. The improvement lies in so detaching the head fromthe associated power-pressure mechanism as to allow it to move up anddown independently of that mechanism and very easily.

It is still another object of the present invention to provide a loadlifting jack of lesser weight than comparable jacks which have been usedheretofore.

It is still yet another object of the present invention to provide aload lifting jack in which a guide member is provided to safely andeasily guide the ends of certain associated links for achieving rapidmovement of a load engaging head.

It is further another object of the present invention to provide a loadlifting jack which is easy to set and drive rapidly.

SUMMARY OF THE INVENTION A load lifting jack comprises a pair of guiderails connected in parallel relation with each other by a pin and aconnecting member, so that a rectangular form frame is provided, alifting arm carrying at one end a load engaging head, a screw shaftrotatably supported within the frame, the screw shaft carrying thereonan internally threaded nut to which the lifting arm is pivoted atanother end, a pair of link members each pivoted at one end with respectto the lifting arm at an intermediate position therealong, a base onwhich the pair of guide rails is pivotally mounted by said pin, the basehaving one or more pairs of laterally aligned notches on its flangedportions with which the other ends of the LII link members areselectively engageable, and a supporting member which rotatably supportsthe shaft at its one end and inside of the frame but bears the thrust ofthe screw shaft.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view ofa jackaccording to the invention in a partially elevated position;

FIG. 1 is a fragmentary perspective view explodedly illustrating inphantom some parts of the jack according to the invention;

FIG. 3 is a vertical section, taken along the line III- III of FIG. 1;

FIG. 4 is a fragmentary perspective exploded view particularly showingthe thrust bearing of the screw shaft; and 1 FIG. 5 is a side elevationof the jack according to the invention and showing its operation. i

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1, and3-5, the jack comprises a pair of parallel guide rails l and 2 eachhaving a U-shaped cross-section. The guide rails are held together atthe left-hand ends in FIG. 1 by the connecting member 5 connectedthereto by means of screws 6 and at the right-hand ends by the pin 4both extremities of which protrude beyond the flanges 12 of the base 3and have enlarged portions to prevent it from falling out. This permitsthe guide rails to be tightly fastened together and still be free toswing on the base 3 by waY of the protrusions of pin 4. The right-handends of the guide rails are held in their positions by the cooperationof the linking member 23 and the flanges 12 of the base, so that theyhave a slight frictional engagement with internal surfaces of theflanges. In this construction, a rectangular frame F formed of the guiderails l and 2, the connecting member 5 and the pin 4 is so provided thatthe open topped portions of the crosssectionally U-shaped guide railsface each other. A lifting arm 7 is provided to move between the fullycollapsed position in which the arm occupies the substantiallyhorizontal position (not shown) and an elevated position in which thearm is substantially vertical as shown in FIG. 1. The lifting arm 7pivotally carries at its free end a load engaging head 8 by means of pin9. A dome-like projection 10 is formed in the surface of the hea'd 8 tomate with a corresponding recess (not shown) of a load when in use it ismoved against the load. The lifting arm 7 is formed of heavy gauge sheetmetal and is broader at the center, where the bending stresses arelargest, than at the ends.

The jack base 3 pivotally connected to the guide rails as abovedescribed consists of a horizontal base plate 11 and a pair ofsubstantially vertical flanges 12 at 0pposite sides of the base plate 11and formed integrally therewith. Two pairs of laterally-aligned notchesl3 and 14 are spaced along the upper portion of each flange. A screwshaft 15 protrudes beyond the connecting member 5 through its bore 39 inwhich the screw shaft is free to rotate. A rotary driving head 16 isfast at one end of the screw shaft 15 and outside of the frame F, whereit can be manually rotated by means of the usual driving handle (notshown). An internally screw threaded nut 17 (FIG. 3) is carried on thescrew shaft 15 and two pins 18 are so screwed into opposite sides of nut17 as to extend horizontally therefrom, perpendicularly to the axis ofthe screw shaft 15. Two rollers 19 of plastic material in this instanceare rotatably mounted on the respective pins 18 and are retained withinthe corresponding U shaped guide rails l and 2 by the inwardly extendingflange portions thereof. The lower end of the lifting arm 7 remote fromthe load engaging head 8 consists of two forked side walls which arepivotally mounted on the pins 18, between the nut 17 and the rollers 19respectively.

A thrust bearing 21 (FIG. 4) is carried on the screw shaft 15 at its endopposite head 16, to facillitate smooth rotation of the screw shaft 15when it is operated against a load in use. As specifically shown in FIG.4, an end of the screw shaft 15 protrudes beyond the linking member 23through its bore 24 in which the end of the shaft 15 is free to rotate.At that extremity of the screw shaft 15 is fastened a nut 22, forresisting thrust load applied across the thrust bearing 21 interposedbetween the linking member 23 and the nut 22 on the shaft 15. The thrustbearing 21 consists of a pair of races 21a and a set of balls 25interposed therebetween. A cover 26 is provided to cover the races whenthe thrust bearing is installed. Two links 27 formed of heavy gaugesheet metal connect the linking member 23 and the base 3 by way of thepins 28 and by way of the other pin 4 put in cooperating holes at bothends of the links respectively, the pins 28 extending horizontally inopposite directions from the linking member 23. It will be noted thatthe both links 27 are secured within the space of the correspondingguide rails 1 and 2 as shown in FIG. 1 and transmit the thrust load fromthe linking member 23 to the pin 4 when the screw shaft 15 is rotated inuse. This construction is effective to enable reduction of the thicknessof the sheet metal of the guide rails below thicknesses which wouldotherwise be thought necessary. The links 27 are formed with noses 27aas shown in FIG. 4 at ends thereof remote from the linking member 23.These noses rest on the base plate 11, and will function as a stops,when clockwise rotation occurs as shown in FIG. 5.

The inwardly-bent ends of a pair of links 29 and 30 (FIG. 2) arepivotally mounted in aligned bores 31 and 32 centrally along the liftingarm 7. The other ends of the links are also inwardly bent for engagementwith the pairs of notches l3 and 14 on the flanges 12 of the base 3.Both links are held together at their bent ends by sleeves 33 and 34.This construction permits the links to be tightly fastened together andstill be free to swing on the lifting arm 7. In FIG. 2, an exploded viewof the links and sleeves is shown in phantom. It will be noted that thesleeve 33 is of a larger external diameter than the internal diameter ofbores 31 and 32 of the lifting arm in which the links are free to swing.The length of the sleeve 33 is so designed as to be identical with thewidth of internal space of the lifting arm 7 so that the links integraltherewith do not in use shift laterally across the axis of the liftingarm 7. On one of the flanges 12 of the jack base 3 there is fastened, bymeans of screws 36 and 37, a guide member arcuately shaped so as to forma guide way slot in cooperation with the upper portion of the flange 12,to limit possible movement of the lower bent portions of the links asthey are transferred from one pair of notches to another. Thisconstruction necessitates less movement of the nut 17 than would be thecase if, the jack head 8 v could not be first moved to nearly thedesired height by moving the lower bent portions to a position nearer ormore removed from the nut. This is true of the lowering motion of thejack head 8, too.

Referring again to the driving head 16 at the end of the screw shaft 15,it is seen that there are two leafs divergently spread from the end ofthe screw shaft. Each of the leafs has a hole 16a of elliptical form,and both are in alignment with each other. Either one of the holesfurther has a narrow biased open-ended slot 16b extending forwardly fromits hole 16a, as shown in FIGS. 1 and 5. When the screw shaft 15 is inuse driven, the head of the driving handle (not shown), somewhat like across, is engaged with one of the driving head 16 with its branchesfirst being put in the hole having no slot while the stem of the handleis in angled relation to the axis of the screw shaft 7. The stem is thenaligned with the axis of the screw shaft so that the other branch of thehandle head will enter into the hole through the slot. Having set theother branch in the hole, the operator then can rotate the handle in thedesired direction, the head 8 being lifted up against the load, orlowered. The narrowness of the slot suffices to prevent the handle headfrom falling out during the operation.

When lifting a load, the screw shaft 15 is rotated in a direction tocause the nut 17 to advance to the right in FIG. 1. In lowering thejack, the reverse of the above action takes place. That is to say, afterrevolution of the screw shaft 15 in the opposite direction until no loadis received by the load engaging head 8, the lower bent portions aremoved to the outer pair of notches 13, if the case may be, to cause thelifting arm I to return to its lower position whereby rapid collapse maybe effected.

The bed 38 fast ongthe under surface of the guide rails is effective tofurther tighten the guide rails to each other and position the drivinghead 16 within convenient reach of the operator.

The device is in principle recognized as a four-sided linkage or quadriccrank chain consistingof four links. The desired mechanical movement ofthe device is derived by the use of combination of proportioned leversand connecting links. The geometry of this linkage is characterized bythe lines B, R1, A1 and L1 as indicated by dot-and-dash linework in FIG.5. It should be noted that the line B which extends from the pin 4 tothe axis of one of pairs of the notches 13 or 14, is always heldstationary.

It will be seen that if guide rails 1 and 2 were held stationary (notpractically possible of course) in use at the position R1 as shown inFIG. 5 and the screw shaft 15 were turned, then the head 8 would travelin a path Pl. Further, it will be seen that if guide rails were heldstationary at the position R2, and the shaft 15 were turned, then thehead 8 would travel in another path P2. The links 29 will swing from theposition L1 to the position L2 as the guide rails swing from theposition R1 to the position R2. Therefore, the linkageof the jack alwayspermits the load engaging head 8 to shift to and fro as indicated by thedouble arrow in FIG. 5, as the load shifts in the horizontal, within theangular range indicated by the oblique shade in the view. Any

- fears that the jack base 3 may slide along the ground or that the jackmay fall will thus'be largely alleviated. The base plate 11 of the jackbase 3, in cooperation with the noses 27a of the links 27, prevents theload engaging head 8 from shifting beyond the path P2 to the right. Thepath P2 should be so calculated that the vertical center line of theload engaging head 8 will not in any event shift to the right beyond theright hand edge of the base 3. This is effective to prevent the jackfrom falling and to provide a better seat of the base on the ground.

The jack according to this invention allows the load to occupy anyposition within the angular range while maintaining the better seat ofthe base on the ground.

What is claimed is:

1. In combination in a load lifting jack, a pair of guide rails, meansconnecting said guide rails in parallel relation with each other toprovide a rectangular frame, an elongated lifting arm having a loadengaging head at one end thereof, a screw shaft rotatably supportedwithin the frame, an internally threaded nut on said screw shaft, meanspivotally mounting the other end of said lifting arm on said nut, linkmembers each pivotally connected at one end with said lifting arm at anintermediate position therealong, a base, means pivotally mounting saidpair of guide rails with said base, said base having flanged portionswith notches spaced along the lengths thereof for selectively receivingthe other ends of said link members, a linking member rotatablysupporting the screw shaft at its one end thereof and inside of saidframe, and means supporting said linking member in relation to said baseand in thrust-receiving relation to said screw shaft.

2. A jack according to claim 1, further comprising a guide member fixedwith one of said flanged portions and, together with the notched partsof said flanged portions, providing a guide way confining the other endof one of said link members and thereby guiding the lower ends of saidlink members to selected ones of said notches.

3. A jack according to claim 1, wherein said means pivotally mountingthe other end of said lifting arm on said nut includes two pinsextending horizontally from opposite sides of said nut, perpendicular tothe axis of the screw shaft, and further comprising rollers of plasticmaterial rotatable on said two pins and within said guide rails.

4. A jack according to claim 3 wherein said guide rails are U-shaped incross-section, the said rollers being retained within both guide railsrespectively by their upright walls so that the internally threaded nutmay be moved in a path provided by the guide rails when the screw shaftis turned.

5. A jack according to claim 1, wherein one end of said screw shaftprotrudes beyond said linking member, wherein said means pivotallymounting said guide rails with said base comprises a pivot pin extendingbetween said rails and in pivotal engagement with said base, and whereinsaid means supporting said linking member includes a thrust bearing, anut fast on the protruding end of said screw shaft, said thrust bearingbeing disposed between said linking member and said nut, two pinsextending horizontally from opposite sides of said linking member,perpendicular to the axis of said screw shaft, and two links eachconnected at one end to the linking member by one of said pins and atthe other end to said pivot pin.

6. A jack according to claim 5, wherein each of said links has at itssaid other end a nose disposed to rest on said base and stop furtherrelative motion between said rails and said base in one angulardirection when the guide rails pivot upwardly about said pivot pin by apredetermined angular amount in said direction.

7. A jack according to claim 1, wherein said means connecting said guiderails includes a connecting member fixed between said rails at one endof said rails, the other end of said screw shaft protruding beyond saidconnecting member, and further comprising a driving head fast at saidother end of said shaft, said head having diverging outwardly-spreadingleafs each with a hole therethrough and at least one of which furtherhas a narrow open-ended slot merging with the hole therethrough, wherebya branch of a driving handle may be entered into and drawn from the holethrough the slot.

UNITED STATES PATENT OFTTCE QERTIFECATE OF CORRECTION 3,746 ,307 DatedJuly 17 1.973

Shinichiro Yamazaki Patent No.

Inventor(s) It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet insert [30] Foreign Application Priority Data July 3,1970 Japan-- -*+=="4558618 and 45-58619 July 3, 1970 Japan--**-' 4567042 Signed and sealed this 8th day of January 1974.

(SEAL) .Attestz EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER 1 ActingCommissioner, of Patents Attesting Officer ORM PO-IOSO (10-69) w p.s.sovsnuyazm rmmme ornc; 190a o-ses-ssm a,

1. In combination in a load lifting jack, a pair of guide rails, meansconnecting said guide rails in parallel relation with each other toprovide a rectangular frame, an elongated lifting arm having a loadengaging head at one end thereof, a screw shaft rotatably supportedwithin the frame, an internally threaded nut on said screw shaft, meanspivotally mounting the other end of said lifting arm on said nut, linkmembers each piVotally connected at one end with said lifting arm at anintermediate position therealong, a base, means pivotally mounting saidpair of guide rails with said base, said base having flanged portionswith notches spaced along the lengths thereof for selectively receivingthe other ends of said link members, a linking member rotatablysupporting the screw shaft at its one end thereof and inside of saidframe, and means supporting said linking member in relation to said baseand in thrust-receiving relation to said screw shaft.
 2. A jackaccording to claim 1, further comprising a guide member fixed with oneof said flanged portions and, together with the notched parts of saidflanged portions, providing a guide way confining the other end of oneof said link members and thereby guiding the lower ends of said linkmembers to selected ones of said notches.
 3. A jack according to claim1, wherein said means pivotally mounting the other end of said liftingarm on said nut includes two pins extending horizontally from oppositesides of said nut, perpendicular to the axis of the screw shaft, andfurther comprising rollers of plastic material rotatable on said twopins and within said guide rails.
 4. A jack according to claim 3 whereinsaid guide rails are U-shaped in cross-section, the said rollers beingretained within both guide rails respectively by their upright walls sothat the internally threaded nut may be moved in a path provided by theguide rails when the screw shaft is turned.
 5. A jack according to claim1, wherein one end of said screw shaft protrudes beyond said linkingmember, wherein said means pivotally mounting said guide rails with saidbase comprises a pivot pin extending between said rails and in pivotalengagement with said base, and wherein said means supporting saidlinking member includes a thrust bearing, a nut fast on the protrudingend of said screw shaft, said thrust bearing being disposed between saidlinking member and said nut, two pins extending horizontally fromopposite sides of said linking member, perpendicular to the axis of saidscrew shaft, and two links each connected at one end to the linkingmember by one of said pins and at the other end to said pivot pin.
 6. Ajack according to claim 5, wherein each of said links has at its saidother end a nose disposed to rest on said base and stop further relativemotion between said rails and said base in one angular direction whenthe guide rails pivot upwardly about said pivot pin by a predeterminedangular amount in said direction.
 7. A jack according to claim 1,wherein said means connecting said guide rails includes a connectingmember fixed between said rails at one end of said rails, the other endof said screw shaft protruding beyond said connecting member, andfurther comprising a driving head fast at said other end of said shaft,said head having diverging outwardly-spreading leafs each with a holetherethrough and at least one of which further has a narrow open-endedslot merging with the hole therethrough, whereby a branch of a drivinghandle may be entered into and drawn from the hole through the slot.